This invention relates to a lubricating system for two-cycle internal combustion engines and more particularly to an improved and simplified arrangement for insuring adequate engine lubrication under all running conditions.
As is well known, two-cycle engines pose certain problems in connection with the design of their lubrication systems. Although it has been proposed to mix lubricating oil with the fuel to lubricate the running components, the ratio of fuel and oil necessary to provide adequate lubrication under different running conditions is not the same. That is, when running under a light load and relatively small throttle opening, the engine can operate on a lesser amount of lubricant than when it is running at a higher load and/or higher throttle opening. The lubricant requirements are, however, not directly related to either engine speed or engine load per se. Thus, engines embodying a fixed ratio of lubricant to fuel may be underlubricated under some conditions and overlubricated under other conditions.
It has been proposed to provide a lubricating system in which a variable output lubricant pump delivers lubricant to the fuel system for mixing with the fuel before delivery to the engine. In accordance with an arrangement proposed by the inventors hereof, as disclosed in Japanese Patent Application No. 56-192062, filed Nov. 30. 1981, the variable output lubricant pump is controlled in accordance with changes in engine speed and throttle opening. Thus, if there is a change in either engine speed or throttle opening, an adequate and proper amount of lubricant will be delivered to the fuel system for induction to the engine. Although such an arrangement obviously has advantages, it is also complicated and adds significantly to the cost of the motor since complicated and expensive throttle and speed controls are required in conjunction with that system.
It is, therefore, a principal object of this invention to provide an improved and simplified arrangement for lubricating two-cycle internal combustion engines.
It is a further object of this invention to provide an improved and simplified lubricating system for two-cycle engines that will provide an optimum degree of lubrication under all conditions.
It is a further object of this invention to provide an improved and simplified variable output lubricant system for two-cycle engines.